1. Field of the Invention
The invention relates generally to methods and apparatus for photorefractive correction of vision, and more particularly to the adjustment of higher order aberrations in consideration of biodynamical and biomechanical responses of the eye.
2. Description of Related Art
The field of photorefractive surgery for vision correction continues to grow rapidly. The number of procedures demanded by consumers is constantly increasing at the same time that researchers and practitioners are learning more about vision and how to correct it. The application of excimer laser technology including refinements in beam size, shape, and placement, active eye tracking, and diagnostic instrument development including topographers, wavefront sensors, ultrasound, and OCT's underscores the progress in this field.
What has become evident as understanding continues to unfold about what perfect vision really is, is that models need to be developed which describe the eye and its various responses to attempts at vision correction. The advent of wavefront sensing in ophthalmology is driving now traditional procedures such as photorefractive keratectomy (PRK) and LASIK which were primarily concerned with correcting refractive errors such as defocus and astigmatism (myopia, hyperopia, and astigmatic forms thereof), to the investigation and performance of more sophisticated procedures in which higher order optical aberrations (herein referred to as third and higher Zernike order or equivalent) are being addressed. These higher order monochromatic aberrations include, for example, spherical aberration, coma, and others as well understood by those skilled in the art.
The inventors of the present invention have recognized that directly eliminating all wavefront aberrations of the eye is not necessarily the key to emmetropia, because the act of photorefractive correction itself induces certain defects that must be accounted for in developing a photorefractive treatment. Accordingly, the invention is directed to methods and apparatus for developing and performing photorefractive treatments in view of these observations and which result in better objective and subjective visual evaluation.